Large diameter and thin wall laser tube bending

2005 ◽  
Author(s):  
Wenwu Zhang ◽  
Marshall Jones ◽  
Michael Graham ◽  
Brian Farrell ◽  
Magdi Azer ◽  
...  
Keyword(s):  
Large Diameter ◽  
Thin Wall ◽  
Tube Bending ◽  
Laser Tube

scholarly journals Experimental Investigation of the Effects of Irradiating Schemes in Laser Tube Bending Process

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1123
Author(s):  
Mehdi Safari ◽  
Ricardo J. Alves de Sousa ◽  
Jalal Joudaki
Keyword(s):  
Laser Beam ◽  
Contact Process ◽  
Steel Tube ◽  
Thickness Variation ◽  
Tube Bending ◽  
Lateral Bending ◽  
Bending Angle ◽  
Laser Tube ◽  
Bending Process ◽  
Thickness Variations

The laser tube bending process (LTBP) process is a thermal non-contact process for bending tubes with less springback and less thinning of the tube. In this paper, the laser tube bending process will be studied experimentally. The length of irradiation and irradiation scheme are two main affecting process parameters in the LTBP process. For this purpose, different samples according to two main irradiation schemes (Circular irradiating scheme (CIS) and axial irradiating scheme (AIS)) and different lengths of laser beam irradiation (from 4.7 to 28.2 mm) are fabricated. The main bending angle of laser-bent tube, lateral bending angle, ovality, and thickness variations is measured experimentally, and the effects of the irradiating scheme and the length of irradiation are investigated. An 18 mm diameter, 1 mm thick mild steel tube was bent with 1100 Watts laser beam. The results show that for both irradiating schemes, by increasing the irradiating length of the main and lateral bending angle, the ovality and thickness variation ratio of the bent tube are increased. In addition, for a similar irradiating length, the main bending angle with AIS is considerably higher than CIS. The lateral bending angle by AIS is much less than the lateral bending angle with CIS. The results demonstrate that the ovality percentage and the thickness variation ratio for the laser-bent tube obtained by CIS are much more than the values associated with by AIS laser-bent tube.

Dynamic Responses of Buried Pipelines Under Impact Loading Caused by Landslide

2012 ◽  
Vol 204-208 ◽  
pp. 3476-3479 ◽  
Author(s):  
Xiu Xing Zhu ◽  
Shi Feng Xue ◽  
Xing Hua Tong ◽  
Chuan Qi Liu
Keyword(s):  
Impact Loading ◽  
Impact Force ◽  
Large Diameter ◽  
Influence Factors ◽  
Dynamic Responses ◽  
Thin Wall ◽  
Buried Pipelines ◽  
Steel Pipes ◽  
Mountainous Regions ◽  
The Impact

Cases of pipeline damage caused by landslide are common in coastal or mountainous regions, where the design of buried pipelines should be improved in order to reduce the risk of damage or failure. Dynamic responses of large diameter thin wall steel pipes under impact loading were analyzed using a nonlinear contact model of pipe-soil coupling in this paper. Several influence factors were studied, such as the impact velocity of rockfall, buried depth of pipeline, ratio of diameter to thickness and style of soil. The results show that an ellipsoid induces much more impact force than a sphere which has the same volume, and the larger one in volume have greater impact force for two spheres. Dangerous compressive areas of pipeline occupy 1/6 of the whole area, so the pipelines subject to landslide occur local failure. Based on results, some useful suggestions for the design of pipelines in landslide region are given

Hot Clamp Design for LMFBR Piping Systems

1993 ◽  
Vol 115 (1) ◽  
pp. 47-52
Author(s):  
T. Kobayashi ◽  
M. Tateishi
Keyword(s):  
Thermal Stresses ◽  
Cost Minimization ◽  
Large Diameter ◽  
Self Control ◽  
Test Facility ◽  
Thin Wall ◽  
Control Effect ◽  
Flexible Pipe ◽  
Pipe Surface ◽  
Thermal Transients

Thin-wall, large-diameter piping for liquid metal fast breeder reactor (LMFBR) plants can be subjected to significant thermal transients during reactor scrams. To reduce local thermal stresses, an insulated “cold” clamp was designed for the fast flux test facility and was also applied to some prototype reactors thereafter. However, the cost minimization of LMFBR requires much simpler designs. This paper presents a “hot” clamp design concept, which uses standard clamp halves directly attached to the pipe surface leaving an initial gap. Combinations of flexible pipe and rigid clamp achieved a self-control effect on clamp-induced pipe stresses due to the initial gap. A 3-D contact and inelastic history analysis were performed to verify the hot clamp concept. Considerations to reduce the initial stress at installation, to mitigate the clamp restraint on the pipe expansion during thermal shocks, and to maintain the pipe-clamp stiffness desired during a seismic event were discussed.

Flexibility Factors and Stress Indices for Piping Components With D/T ≧ 100 Subjected to In-Plane or Out-of-Plane Moment

1988 ◽  
Vol 110 (4) ◽  
pp. 374-386 ◽  
Author(s):  
T. Fujimoto ◽  
T. Soh
Keyword(s):  
Finite Element ◽  
Wall Thickness ◽  
Large Diameter ◽  
Thin Wall ◽  
Finite Element Analyses ◽  
Empirical Formulas ◽  
Stress Evaluation ◽  
Stress Indices ◽  
Piping Systems ◽  
Out Of Plane

The finite element analyses are carried out for the several piping components (D/T ≧ 100) subjected to in-plane or out-of-plane moment. For the stress evaluation of the chemical plant piping systems, ANSI B31.3 is usually applied. But the stress intensification factors and flexibility factors in this code are mainly for a heavy-wall-thickness pipe, so it is necessary to reconsider these factors for a thin-wall-thickness pipe with a large diameter. In our study, several finite element analyses using MSC/NASTRAN program were performed on the pipe bends (elbow or miter bend, 0.01 ≦ h ≦ 0.2) and the unreinforced fabricated tees (50 ≦ D/Tr ≦ 300, 0.5 ≦ d/D ≦ 0.95, 0.25 ≦ Tb/Tr ≦ 0.95), and the empirical formulas for the flexibility factors and the stress indices, due to out-of-plane or in-plane moment, were proposed. Experimental stress analyses for the piping components with D/Tr = 127 were also carried out, and it was confirmed that the results agreed well with the numerical ones.

Development of Flexible Bellows for Large Diameter, Multi Layered and Thin Wall Thickness Stainless for LNG(-161.DEG.C.) Transportation Use.

Materia Japan ◽  
1994 ◽  
Vol 33 (5) ◽  
pp. 650-652
Author(s):  
Yoshiyuki Tashiro ◽  
Shin Kinoshita ◽  
Toshimi Yamane ◽  
Keiichi Hirao ◽  
Shin-ichiroh Yokoyama
Keyword(s):  
Wall Thickness ◽  
Large Diameter ◽  
Thin Wall

scholarly journals Buckling of Imperfect, Axisymmetric, Homogeneous Shells of Variable Thickness: Perturbation Solution

2005 ◽  
Author(s):  
Dennis Williams
Keyword(s):  
Cylindrical Shell ◽  
Variable Thickness ◽  
Large Diameter ◽  
Compressive Load ◽  
Thin Wall ◽  
Shells Of Revolution ◽  
Equilibrium Equations ◽  
Asme Code ◽  
Current Design ◽  
Section Viii

This paper presents the first of a series of solutions to the buckling of imperfect cylindrical shells subjected to an axial compressive load. In particular, the initial problem reviewed is the case of a homogeneous cylindrical shell of variable thickness that is of an axisymmetric nature. The equilibrium equations as first introduced by Donnell over seventy years ago are thoroughly presented as a basis for embarking upon a solution that makes use of perturbation methods. The ultimate objective of these calculations is to achieve a quantitative assessment of the critical buckling load considering the small axisymmetric deviations from the nominal shell wall thickness. Clearly in practice, large diameter, thin wall shells of revolution that form stacks (as found in flue gas desulphurization absorber assemblies) are never fabricated with constant diameters and thicknesses over the entire length of the assembly. As such, ASME Boiler and Pressure Vessel Code Section VIII fabrication tolerances as supplemented by ASME Code Case 2286-1 are reviewed and addressed in light of the findings of the current study and resulting solutions with respect to the critical buckling loads. The method and results described herein are in stark contrast to the “knockdown factor” approach currently utilized in ASME Code Case 2286-1. Recommendations for further study of the imperfect cylindrical shell are also outlined in an effort to improve on the current design rules regarding column buckling of large diameter shells designed in accordance with ASME Section VIII, Divisions 1 and 2; and ASME STS-1 in combination with the suggestions contained within Code Case 2286-1.

Development of a Crack Opening Displacement Assessment Procedure Considering Change of Compliance at a Crack Part in Thin Wall Pipes Made of Modified 9Cr-1Mo Steel

2018 ◽  
Author(s):  
Takashi Wakai ◽  
Hideo Machida ◽  
Manabu Arakawa ◽  
Seiji Yanagihara ◽  
Ryosuke Suzuki ◽  
...  
Keyword(s):  
Crack Opening Displacement ◽  
Work Hardening ◽  
Crack Opening ◽  
Large Diameter ◽  
Assessment Method ◽  
Leak Rate ◽  
Thin Wall ◽  
Opening Displacement ◽  
Thin Walled ◽  
Small Work

This study was carried out to establish crack opening displacement (COD) evaluation methods used in Leak-Before-Break (LBB) assessment of thin-walled large-diameter pipes of the Sodium cooled Fast Reactors (SFRs). For the pipes of SFR, the continuous leak monitoring will be adopted as an alternative to a volumetric test of the weld joints under conditions that satisfy LBB. The sodium pipes are made of ASME Gr.91 (modified 9Cr-1Mo steel). Thickness of the pipes is small, because the internal pressure is very small. Modified 9Cr-1Mo steel has a relatively large yield stress and small work hardening coefficient comparing to the austenitic stainless steels which are currently used in the conventional plants. In order to assess the LBB behavior of the sodium pipes made of modified 9Cr-1Mo steel, the coolant leak rate from a through wall crack must be estimated properly. Since the leak rate is strongly related to the crack opening displacement (COD), an appropriate COD assessment method must be established to perform LBB assessment. However, COD assessment method applicable for SFR pipes — having thin wall thickness and made of small work hardening material — has not been proposed yet. Thus, a COD assessment method applicable to thin walled large diameter pipe made of modified 9Cr-1Mo steel was proposed in this study. In this method, COD was calculated by classifying the components of COD; elastic, local plastic and fully plastic. In addition, the verification of this method was performed by comparing with the results of a series of four-point bending tests using modified 9Cr-1Mo steel pipe having a circumferential through wall notch. As a result, in some cases, COD were overestimated especially for large cracks. Although the elastic component of COD, δEE, is still over-estimated for large cracks, leak evaluation from small cracks is much more important in LBB assessment. Therefore, this study recommends that only the elastic component of COD, δEE, should be adopted in LBB assessment of SFR pipes.

Experimental study of large-diameter thin-wall pressure vessels

1961 ◽  
Vol 1 (2) ◽  
pp. 33-42 ◽  
Author(s):  
A. J. Durelli ◽  
J. W. Dally ◽  
S. Morse
Keyword(s):  
Experimental Study ◽  
Large Diameter ◽  
Pressure Vessels ◽  
Wall Pressure ◽  
Thin Wall
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